Physiology and Pathophysiology of Apolipoprotein E receptor-2 splicing in Alzheimer's disease

阿尔茨海默病中载脂蛋白 E 受体 2 剪接的生理学和病理生理学

• 批准号: 9159262
• 负责人: Joachim J Herz
• 金额: $ 202.48万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-15 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9159262
• 关键词: Address; Affect; Age; Alleles; Alternative Splicing; Alzheimer' s Disease; American; Amyloid; Amyloid beta-Protein Precursor; Apolipoprotein E; Behavior; Brain; CCL4 gene; Carrier Proteins; Cell Nucleus; Cholesterol; Cleaved cell; Clinical; Cognition; Cognitive deficits; Cytoplasmic Tail; Dendritic Spines; Due Process; Elderly; Endocytosis; Endosomes; Event; Exons; Extracellular Domain; Failure; Fright; Functional disorder; Gene Expression; Gene Family; Genes; Genetic Transcription; Glutamate Receptor; Hippocampus (Brain); Homeostasis; Human; Impaired cognition; Knock-in Mouse; Knock-out; Knockout Mice; LDL-Receptor Related Protein 1; Late Onset Alzheimer Disease; Learning; Left; Ligands; Link; Low Density Lipoprotein Receptor; Mediating; Memory; Memory Loss; Metalloproteases; Modeling; Modification; Mus; Neurodegenerative Disorders; Neurons; Neurotransmitters; Pathogenesis; Peptides; Peripheral; Physiological; Physiology; Process; Protein Isoforms; Proteins; Proteolysis; Proteolytic Processing; RNA Splicing; Receptor Activation; Receptor Gene; Recycling; Regulation; Reporting; Resistance; Risk Factors; Role; Signal Transduction; Source; Structure; Synapses; Testing; Therapeutic; Toxic effect; Trademark; VLDL receptor; Variant; Vertebral column; Work; amyloid formation; amyloid precursor protein processing; apolipoprotein E receptor 2; apolipoprotein E-4; density; extracellular; fear memory; gamma secretase; glycosylation; high risk; in vivo; member; mutant; neurotransmission; novel therapeutics; overexpression; prevent; progressive neurodegeneration; protective effect; receptor; sugar; synaptic function; synaptogenesis; trafficking

PROJECT SUMMARY According to the most recent Alzheimer's Association report, 2015 Alzheimer's Disease Facts and Figures, one out of nine Americans over the age of 65 has Alzheimer's Disease (AD) and an estimated 40-65% of them carry at least one copy of the ε4 allele of gene for a cholesterol transport protein, apolipoprotein E (ApoE). Despite being one of the highest risk factors for AD (second only to age), the mechanism by which ApoE4 increases AD occurrence is unknown. ApoE transports cholesterol to neurons via ApoE receptors, which are members of the low density lipoprotein (LDL) receptor gene family. Some of these ApoE receptors, i.e. LRP1, Apoer2, VLDL receptor (Vldlr), and Lrp4, are intrinsic components of central and peripheral synapses, where they serve as essential regulators of neurotransmission through cytoplasmic signaling and neurotransmitter trafficking. The progressive neurodegeneration in AD first presents as memory loss brought on by synaptic dysfunction. Amyloid-β (Aβ), the central component in the trademark plaques that build up in the brains of people with AD, are a product of the amyloid precursor protein, APP, and a likely source of this early dysfunction. We have shown previously that Aβ-induced synaptic suppression can be prevented through ApoE receptor activation and ApoE4 selectively impairs this synaptoprotective function by sequestering the ApoE receptor, Apoer2. Apoer2, an essential CNS ApoE receptor, is endogenously expressed in multiple alternatively spliced forms, indicating a physiological need for functionally diverse forms of the receptor. We have found that differential splicing of an extracellular O-glycosylation domain dramatically alters Apoer2 abundance, synaptic function and fear memory. Apoer2 can also modify the formation of Aβ through multiple interactions with APP that effect APP processing. Therefore, understanding the regulation and function of Apoer2 is central to understanding the mechanisms by which ApoE4 causes synaptic dysfunction in AD. Accumulating evidence has identified Apoer2 as a key regulator of synaptic homeostasis. In this application, we propose to investigate the consequences of the two main physiological splicing events of Apoer2 on gene expression, protein interactions, behavior and cognition. In Aim 1 we will employ Apoer2- deficient mice and mice expressing various splice forms of Apoer2 to explore how Apoer2 regulates gene expression. In Aim 2, we will explore the protein interactome of these Apoer2 isoforms and probe how the various ApoE isoforms affect their trafficking and signaling, as well as their ability to regulate APP processing. In Aim 3, we will explore how endogenous Apoer2 splice variants modify behavior and cognition and how they affect cognitive deficits in mice with human ApoE isoforms or Aβ-overproduction.

项目概要 根据阿尔茨海默病协会最新报告《2015 年阿尔茨海默病事实和数据》， 65 岁以上的美国人中，九分之一患有阿尔茨海默病 (AD)，估计其中 40-65% 携带至少一个胆固醇转运蛋白、载脂蛋白 E (ApoE) 基因的 ε4 等位基因拷贝。 尽管 ApoE4 是 AD 的最高风险因素之一（仅次于年龄），但其机制 AD 发生率的增加尚不清楚。 ApoE 通过 ApoE 受体将胆固醇转运至神经元，这些受体是 低密度脂蛋白（LDL）受体基因家族的成员。其中一些 ApoE 受体，即 LRP1， Apoer2、VLDL 受体 (Vldlr) 和 Lrp4 是中枢和外周突触的固有成分，其中 它们通过细胞质信号传导和神经递质作为神经传递的重要调节剂 贩运。 AD 中的进行性神经变性首先表现为突触引起的记忆丧失 功能障碍。 β 淀粉样蛋白 (Aβ)，是大脑中形成的标志性斑块的核心成分 患有 AD 的人是淀粉样前体蛋白 APP 的产物，并且可能是这种早期的来源 功能障碍。我们之前已经证明，Aβ 诱导的突触抑制可以通过 ApoE 来预防 受体激活和 ApoE4 通过隔离 ApoE 选择性地损害这种突触保护功能 受体，Apoer2。 Apoer2 是一种重要的 CNS ApoE 受体，在多种细胞中内源表达 选择性剪接形式，表明生理学上需要功能多样的受体形式。我们 发现细胞外 O-糖基化结构域的差异剪接极大地改变了 Apoer2 丰富性、突触功能和恐惧记忆。 Apoer2还可以通过多种方式改变Aβ的形成 与影响APP处理的APP交互。因此，了解其调节和功能 Apoer2 对于理解 ApoE4 导致 AD 突触功能障碍的机制至关重要。 越来越多的证据表明 Apoer2 是突触稳态的关键调节因子。在这个 应用中，我们建议研究两个主要生理剪接事件的后果 Apoer2 对基因表达、蛋白质相互作用、行为和认知的影响。在目标 1 中，我们将采用 Apoer2- 缺陷小鼠和表达Apoer2各种剪接形式的小鼠探索Apoer2如何调节基因 表达。在目标 2 中，我们将探索这些 Apoer2 同工型的蛋白质相互作用组，并探讨如何 各种 ApoE 亚型影响其运输和信号传导，以及调节 APP 加工的能力。 在目标 3 中，我们将探讨内源性 Apoer2 剪接变体如何改变行为和认知以及它们如何 影响具有人类 ApoE 同工型或 Aβ 过量产生的小鼠的认知缺陷。